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LY4064809

Phase 3

Breast Neoplasms | Small molecule | Oncology |Eli Lilly and Company|Last Updated: Aug 21, 2026

Target and mechanism

Molecular targetPIK3CA
Target classGene
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials1
Total Enrollment800

FDA Designations

No designations recorded

Clinical trial landscape

LY4064809 · 4 trials · 3 indications

Phase 3 1Phase 1 3
NCT07174336A Study of Tersolisib (LY4064809/STX-478) With Other Anti-Cancer Treatments in Participants With Advanced Breast Cancer With a Genetic Change (PIK3CA)Breast Neoplasms
RECRUITING800 Analytics
PHASE3RECRUITING
A Study of Tersolisib (LY4064809/STX-478) With Other Anti-Cancer Treatments in Participants With Advanced Breast Cancer With a Genetic Change (PIK3CA)
Breast NeoplasmsUnlock trial analytics

Study Endpoints

Primary Endpoints

(Part 1): Overall Response Rate (ORR): Percentage of Participants with Confirmed Complete Response (CR) or Partial Response (PR)
Baseline through disease progression or death (Estimated up to 5 years)

As determined by the investigator based on Response Evaluation Criteria in Solid Tumors (RECIST) v 1.1

(Part 2): Progression-Free Survival
Baseline to objective progression or death due to any cause (Estimated up to 5 years)

Investigator-assessed

To determine the absolute bioavailability (F) of LY4064809 following administration of a single oral dose compared to an intravenous reference dose in healthy participants.
Baseline up to Day 14
Pharmacokinetics (PK): Maximum Concentration (Cmax) of LY4064809
Predose on Day 1 Through Day 14

PK: Cmax of LY4064809

PK: Area Under the Concentration Versus Time Curve (AUC) of LY4064809
Predose on Day 1 Through Day 14

PK: AUC of LY4064809

Pharmacokinetics (PK): Area Under the Concentration versus Time Curve from Time Zero to Time T (AUC 0-tlast)
Day 1 to Approximately Day 47

PK: AUC 0-tlast, where t is the last time point with a measurable concentration

Pharmacokinetics (PK): Area Under the Concentration versus Time Curve from Zero to Infinity (AUCinf)
Day 1 to Approximately Day 47

PK: AUCinf

Secondary Endpoints

(Part 1): Disease Control Rate (DCR)
Baseline through measured progressive disease (Estimated up to 5 years)
(Part 1): Time to Response (TTR)
Baseline until the date that measurement criteria for CR or PR (whichever is first recorded) are first met (Estimated as approximately 5 years)
(Parts 1 and 2): Duration of Response (DOR)
Date of CR or PR to date of objective disease progression or death due to any cause (Estimated up to 5 years)
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Study Design & Arms

AllocationRANDOMIZED
MaskingDOUBLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
LY4064809 + CDK4/6 Inhibitor + Endocrine Therapy (ET) (Part 1)EXPERIMENTALLY4064809 given orally in one of two doses in combination with investigator's choice of CDK4/6 inhibitor given orally and ET given orally or intramuscularly
LY4064809 + CDK4/6 Inhibitor + Endocrine Therapy (ET) (Part 2)EXPERIMENTALLY4064809 given orally in combination with CDK4/6 inhibitor given orally and ET given orally or intramuscularly
Placebo + CDK4/6 Inhibitor + Endocrine Therapy (ET) (Part 2)PLACEBO_COMPARATORPlacebo given orally in combination with CDK4/6 inhibitor given orally and ET given orally or intramuscularly
LY4064809EXPERIMENTAL -
Group 1 Treatment A FastedEXPERIMENTALLY4064809 administered orally
Group 1 Treatment B High-Fat MealEXPERIMENTALLY4064809 administered orally
Group 2 Treatment A FastedEXPERIMENTALLY4064809 administered orally
Group 2 Treatment C Proton Pump Inhibitor (PPI) EffectEXPERIMENTALLY4064809 administered orally with esomeprazole

Interventions

NameTypeDescription
LY4064809DRUGAdministered orally
PlaceboDRUGAdministered orally
RibociclibDRUGAdministered orally
PalbociclibDRUGAdministered orally
AbemaciclibDRUGAdministered orally
AnastrozoleDRUGAdministered orally
LetrozoleDRUGAdministered orally
ExemestaneDRUGAdministered orally
FulvestrantDRUGAdministered intramuscular
[14C]-LY4064809DRUGAdministered by IV infusion
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites359

Inclusion Criteria: * Are willing to follow contraception requirements. Contraceptive use by participants should be consistent with local regulations regarding the methods of contraception for those participating in clinical trials. * If assigned female at birth, pre-/peri- and postmenopausal statu...

Countries:United StatesArgentinaAustraliaBelgiumBrazilCanadaChinaFranceGermanyGreeceIrelandItalyJapanSingaporeSouth KoreaSpainTaiwanTurkey (Türkiye)United Kingdom
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Recent Changes (Last 90 Days)

LOWAug 21, 2026NCT07174336lastUpdatePostDate: changed
LOWAug 21, 2026NCT07174336lastUpdatePostDate: changed
LOWAug 6, 2026NCT07174336lastUpdatePostDate: changed
LOWAug 6, 2026NCT07174336lastUpdatePostDate: changed
LOWJul 30, 2026NCT07174336Enrollment: 920 → 800
LOWJul 30, 2026NCT07174336Enrollment: 920 → 800
MEDIUMJul 9, 2026NCT07519525TRIAL_REMOVED: changed
MEDIUMJul 9, 2026NCT07519525TRIAL_REMOVED: changed
MEDIUMJul 9, 2026NCT07519525TRIAL_REMOVED: changed
LOWJul 7, 2026NCT07174336lastUpdatePostDate: changed
LOWJul 7, 2026NCT07174336lastUpdatePostDate: changed
LOWJun 23, 2026NCT07174336lastUpdatePostDate: changed
LOWJun 23, 2026NCT07174336lastUpdatePostDate: changed
HIGHJun 8, 2026NCT07519525Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHJun 8, 2026NCT07519525Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHJun 8, 2026NCT07519525Status: ACTIVE_NOT_RECRUITING → COMPLETED

Frequently asked questions about LY4064809

What is LY4064809 used for?

LY4064809, also known as tersolisib, is an investigational small molecule being studied for the treatment of advanced breast cancer with a PIK3CA genetic change. It is being evaluated in combination with other anti-cancer treatments in a Phase 3 clinical trial enrolling participants with breast neoplasms and metastasis.

What does LY4064809 target?

LY4064809 targets the PIK3CA gene. It is being studied in patients whose tumors carry a PIK3CA genetic change, as part of a Phase 3 trial for advanced breast cancer. The drug is designed to act on this specific genetic alteration.

Who makes LY4064809?

LY4064809 is being developed by Eli Lilly and Company, a pharmaceutical company listed on the stock exchange under the ticker LLY. The drug is also known as tersolisib and is currently in clinical development for oncology indications.

What phase is LY4064809 in?

LY4064809 is in Phase 3 clinical development for advanced breast cancer with a PIK3CA genetic change. It is an investigational drug and has not been approved by regulatory authorities. Earlier Phase 1 studies in healthy participants have been completed.

What clinical trials is LY4064809 in?

LY4064809 is being studied in a Phase 3 trial, NCT07174336, which is recruiting 800 participants with advanced breast cancer and PIK3CA mutations across multiple countries. Additional Phase 1 studies in healthy participants, including NCT07247357, NCT07339735, and NCT07519525, have been completed.

Is LY4064809 the same as tersolisib?

Yes, LY4064809 is also known as tersolisib. The Phase 3 clinical trial for advanced breast cancer refers to the drug as tersolisib (LY4064809/STX-478). Both names refer to the same investigational small molecule being developed by Eli Lilly and Company.